The invention more particularly concerns facilities for manufacturing and/or processing and/or filling hollow bodies.
By way of example, the invention will be described within the scope of a facility for manufacturing and/or filling containers made of thermoplastic material. More particularly, the device according to the invention will be described within the scope of a machine for manufacturing polyethylene terephtalate (PET) bottles in which the bottles are obtained by blow-molding a preform that has first been produced by injection molding.
In such facilities, it is often necessary, at one point or another in the process of manufacturing, processing or filling, to inject a product into a hollow body. For example, in a bottle manufacturing or filling unit, this product can be a sterilizing agent.
These facilities generally operate continuously, the hollow bodies all following the same path in the facility, moving continuously one after the other. This continuous nature of the movement of the hollow bodies poses a problem with respect to injecting into each hollow body a product such as a sterilizing agent. Indeed, there are generally two solutions.
According to one of these solutions, the simplest one, the product is injected by a nozzle placed in each hollow body when the hollow body in question passes in front of the nozzle. However, in high speed facilities, the length of time the hollow body is in front of the nozzle is extremely short, making it difficult to spray a sufficient amount of product under good spraying conditions, particularly when it is desired to ensure a good distribution of the product injected into the hollow body. In order to inject the desired amount of product, the flow rate of product must be increased, with the consequent loss of good control of the jet. The spray could also be begun early and its ending delayed, at the risk of part of the product not being injected into the hollow body, which causes wastage of product and fouling of the outside of the hollow body and the machine.
Another solution would consist of using a specific machine similar to a rotary filling machine. However, the cost of such a solution would be much too high.
A purpose of the invention, therefore, is to propose a new design of an injection device that is simple and reliable, and which allows a product to be injected into a moving hollow body, the conditions of injection of the product being perfectly controlled.
To that end, the invention proposes a device for injecting a product toward a predetermined location of objects that are moving continuously along a given path while being spaced from each other at a specific distance, characterized in that the device has a series of injectors that are carried by a movable support while being spaced on the support at a distance corresponding to that of the objects, in that the support is driven in a reciprocal movement so that, during an outbound phase of the movement the injectors are each moved in front of the predetermined location of one of the objects, and in that the period of the reciprocal movement of the support is equal to the time interval between the passage of two consecutive objects before a same fixed point, multiplied by the number of injectors on the support.
According to other characteristics of the invention:
during the outbound phase of the movement, the injectors are moved parallel to and at the same speed as the objects;
the reciprocal movement of the support has, in addition to the outbound phase, a return phase during which the movement is in the reverse direction, and two reversal phases;
the duration of the four phases of movement are of the same order of magnitude;
all along the reciprocal movement, the path of the injectors remains parallel to the path of the objects;
the path of the injectors is a semicircular arc;
the device has a transfer wheel that is driven in continuous rotational movement around its axis and on which are loaded the objects along one part of their path, and the injectors follow a path in an arc of circle around the same axis;
the reciprocal movement of the movable support is controlled by a system having a movable cam and a cam follower connected to the support;
the cam is a rotary cam that is driven in continuous rotational movement;
the cam is driven in a continuous rotational movement around an axis parallel to the axis of rotation of the support;
the cam has the form of a plate the contour of which forms the cam path;
the cam follower is pressed against the cam by elastic return means;
the device has a second cam that cooperates with a second cam follower connected to the support, and the profiles of the two cams are complementary so as to ensure positive control of the support in both directions of its reciprocal movement;
at least one of the two cam followers has elastic means suitable for compensating for the geometric imperfections of the device;
it has a plate in which a track is formed with two parallel edges in which a roller moves that is connected to the support and which can cooperate with each of the edges of the track, these two edges each forming a cam path to ensure positive control of the support in both directions of its travel;
the cam is driven in rotation by the transfer wheel through a reduction gear;
the objects are hollow bodies having one opening; and
the injectors are provided to inject a product into the hollow bodies.